The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent it is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Interactive digital maps, which various geographic applications display on computing devices, generally depict numerous geographic features, such as roads, outlines of countries and towns, bodies of water, buildings, etc. Geographic features displayed as part of a digital map can have different appearance at different levels of magnification of the digital map. In general, new details in feature geometry, as well as more subtle variations in color, emerge when the virtual camera approaches a certain area. Moreover, some of geographic features can be depicted differently in different contexts. For example, a road normally depicted as a blue line can be rendered in red to illustrate heavy traffic, or the boundary of a county can be highlighted in response to a geographic query.
In addition to providing top-down views of digital maps, some geographic applications tilt the map plane in some situations to make the upper portion of the map appear farther away from the virtual camera than the lower portion of the digital map. Generating such views seamlessly, where the individually features are rendered consistently with the tilt, presents numerous technical difficulties. It is particularly difficult to generate such views efficiently.